Correlation between birefringent bands and shear bands in surfactant solutions

Abstract

We ask the question of whether birefringent bands observed during stress plateaus when shearing certain surfactant solutions correspond to shear banding, i.e., a region of high shear rate coexisting with a region of low shear rate. Our experimental observations on one surfactant system agree with the simple idea of a shear-induced transition between a high and a low viscosity ‘phase’. The detailed analysis of the velocity profiles allows us to reach the conclusion that the viscosities of the coexisting phases are those of the homogeneous fluids that exist before and after the stress plateau. The proportion of the shear-induced phase grows in the same fashion as that of the birefringent band, and the fraction of the gap occupied by the shear-induced fluid is found to follow a simple lever rule.

Flow of wormlike micelle solutions through a periodic array of cylinders

“…The critical shear Deborah number for the onset of shear banding was found to be De crit = 2.0 for the 100/50 mM CPyCl-NaSal solution. Although, we have not yet attempted to observe shear-banding in the CTAB-NaSal solutions, it could also account for the dramatic reduction in the shear viscosity observed in these systems and has been observed in the past for other CTAB solutions [57][58][59]. For the data presented in Fig.…”

Some Applications of Magnetic Resonance Imaging in Fluid Mechanics: Complex Flows and Complex Fluids

“…Figure 10 also shows a clear discontinuity in slope in the profile, corresponding to the low-and high-shear band. Drappier et al (2006) were able to locate the average position of the interface rather precisely, although large fluctuations in the interface position have been observed in similar systems (Becu et al 2004, Holmes et al 2003, Lopez-Gonzalez et al 2004. Width of the shear band relative to the gap width from magnetic resonance imaging (MRI) velocity profiles compared with those measured using birefringence of and to the theoretical prediction from a simple lever rule.…”

Temperature and concentration influence on drag reduction of very low concentrated CTAC/NaSal aqueous solution in turbulent pipe flow

“…So [13,14] studied the impact of a wall slip. Some other questions are asked in the review paper of Drappier et al [15]. Direct Numerical Simulations have been made during the last 15 years ( [16], and cited by [3][4][5]).…”